Actuating pressure release system



Feb. 23, 1960 j, B, OTTESTAD 2,925,802.I

ACTUATING PRESSURE RELEASE SYSTEM .mmw

Feb. 23, 1960 J. a'o'rTl-:STAD 2,925,803

ACTUATING PRESSURE RELEASE SYSTEM Filed Dec. 16, 1958 2 Sheets-Sheet 2 gi j; .-II

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UnitedStates Patent O 19 Claims. (Cl. 121-38) p This invention relates generally to actuators, more particularly, it relates to an actuator utilizing a novel pressure release system for rapid release of actuating pressure upon an actuating piston.

The present invention is adapted for very rapid production of output thrust or acceleration and is related generally to the actuators described and claimed in the copending application of .Tack Benton Ottestad, Serial No. 617,014, filed October 19, 1956, the copending application of J ack Benton Ottestad and Samuel Arthur Skeen, Serial No. 683,855, iiled September 13, 1957, and the copending application of Jack Benton Ottestad and Samuel Arthur Skeen, Serial No. 690,744, tiled October 17, 1957. IIn each of the actuators of these applications, a setting pressure urges an actuating piston toward an oriiice wall and causes a sealing element to eiect a positive pressure seal about the orice between the wall and the piston. An actuating pressure is applied through the oriiice upon the portion of the piston within the seal. In certain embodiments of these actuators, the actuating pressurel is increased to overbalance the force of the setting pressure and move the piston from the orice wall. This eliminates the pressure seal and releases the actuating pressure upon an area of the piston outside the sealing element. High output thrust is thereby produced on the piston. In certain other embodiments, means are provided for applying externally controlled triggering force to the actuator piston. This force cooperates with the force of the actuating pressure on the piston area within the seal to eliminate the pressure seal and release the actuating pressure upon the piston area outside the seal.

The actuators of the copending applications are characterized by certain limitations and shortcomings. Among these are that the pressure or force opposes acceleration of the actuator piston and detracts from useful actuator output. An important limitation is that, in order to increase the output force on the actuator piston, the oriiice must be reduced in size to decrease the piston area within the pressure seal relative to the total area acted upon by the actuating pressure after the seal is eliminated. The smaller orifice produces increased orifice losses which detract from useful actuator output. Therefore, a compromise must be made between the conflicting considerations of minimizing the orifice losses and minimizing the piston area within the seal.` i

In overcoming the foregoing limitations and in achieving its objects and advantages, the present invention utilizes a novel actuating pressure release system wherein a separate release piston confronts one side of an orifice wall and an actuator piston is positioned on the opposite side of the orice wall. The release piston and the wall are adapted to cooperate to provide a circular pressure seal around the orice. The release piston is urged by a set force or set pressure into engagement with the orifice wall to establish this pressure seal.

An actuating pressure is applied to an area lof the release piston outside the circular seal to oppose the set force. The release piston is thenv accelerated fromv the orice wall to release the actuating pressure through the orifice upon the actuator piston, either by increasing the actuating pressure to overbalance the set force and eliminate the pressure seal to expose the releasepiston area Within the seal to the actuating pressure, or by utilizing a separate triggering force to overbalance the set force and release the actuating pressure upon the release piston4 area within the seal. The triggering force may be provided by atriggering pressure applied to the release piston area within the seal to cooperate with the actuating pressure in overbalancing the set force.

The novel arrangement of the present invention provides valuable results. An important advantage is that movement of the actuator piston is not opposed by the set force. Increased useful output force, acceleration and velocity are therefore provided. Because the actuating, pressure is rapidly released against the entire cross-- sectional area of the actuator piston,.increased actuator output is provided. Important results are derived from the novel arrangement wherein the set force is balanced by the action of the actuating pressure upon the release piston area outside the pressure seal and wherein the piston area within the seal is exposed to the actuating pressure upon elimination of the pressure seal. fIhe force which is thus rapidly applied to accelerate thel release piston' from the orifice plate is increased by increasing the oriice size to increase the proportion of piston area which is acted upon by the actuating pressure.: after the seal is eliminated. The acceleration of the re.

lease piston and the rate of release of pressure through the orice are increased. Increasing the orifice size reduces the orice losses and thereby increases the useful actuator output. Improved actuator output therefore results from the combined effects of reduced orifice losses and more rapid release of pressure through the orice upon the actuator piston.

-1t` is therefore an object of the present invention toA alleviate the foregoing and other limitations by providing an actuator having novel means for releasing actuating pressure upon an actuator piston.

lt is an object of this invention to provide a novel system for very rapidly releasing pressure. An object of the present invention is an actuator which provides improved output through the utilization of a novel pressure release system for rapid application of actuating pressure.

It is an object of the present invention to provide an actuator, the output of which is substantially unrestricted by internal pressures, forces, or orifice losses.`

An object of this invention is the provision of an actuator wherein actuator piston movement iss'ubstantially unopposed by internal pressures or forces. lt is' an object of the present invention to provide an improved actuator wherein actuating pressure is very rapidly released through an orifice upon an actuator piston with low orice losses.

An object of the present invention is the provision of a novel actuator wherein improved output results from Very rapid release of actuating pressure through a relatively large oriiice upon a large actuator piston area.

lt is another object of this invention to provide a novel actuator wherein very rapid acceleration ofthe release piston from an orice elects very rapid release of pressure against an actuator piston.

Another object of the present invention is the provision of an actuator wherein a relatively high proportion of a release piston area is rapidly exposed toan actuating pressure to rapidly release the pressure upon an actuator piston. i

Other objects y Patented Feb. 23,-1960 the provision of and features of the present invention, as wellas'many advantages thereof, will become appar-f portion of fthecircular base member entro -those'skilled in the art from a consideration of the following description, the appended claims, and the accompanying drawings, in which:

Figure l is an elevational view, showingv a preferred embodiment of the actuator` of.` the present invention;

Figurev 2 is an elevational sectionalview showing de.- tails' of thef actuator Figure 3 is a fragmentary sectional 'view showing certain details scale;

Figure 4is a fragmentary sectional view showing the actuator of Figure 2 during operation;

Figure 5 is a fragmentary sectional view of a modified form of the actuator of 'the present invention; and

Figure 6` is a fragmentary sectionalview taken at line 6-6 of Figure 5.

Referring tothe drawings, and particularly to Figures 1 -and 2, there is shown a preferred embodiment ofthe actuator off the present invention. The actuator assembly includes a base member 10, an end `member L12, an orifice plate or wall14, and cylindrical sections 16 and 18, whichiare secured in clamped relation by tie-bolts 20. The tie-bolts extend through appropriately arranged openings in a ange portion 22-of the end member and engage threaded openings 24 in the base membr 10. The actuator assembly is secured to a wall or foundation 26 'by bolts 28which extend through openings-in a ange 10. Pressure sealing for the actuator housing is provided by resilient seal rings in appropriate grooves in the orifice plate or wall 14, inthe base member and in the end member. The cylindrical actuator housing may be considered as divided into pressure chambers 30 wall. An orifice 34. in the orifice plate interconnects these chambers. for a purpose which is hereinafterI eX- plained.

An actuator.

in Figure 2. An annular sealing element 38` ina peripheral groove in the pis-ton provides pressure sealing between the actuator piston and cylindrical sectionr18.

Bearing rings are disposed in'recesses on veither side of the sealing element to reduceV sliding friction and.to maintain alignment between the piston` and thezcylindri-` cal section. A reduced end portion of a thrust column 40 is secured in a threaded axial opening. 42 `in `the actuator piston. extends through an axial opening in end member -12v and is slidably received in ka bearing: 44 which'is disposed within an enlarged portion of the opening and-retained by a locking ring 46. A resilient annularsealing element in a groove within the opening provides .pressurexsealing A release system assembly v4S is isecuredito the orificeI plate, as shown in Figuresd and 2. A-cap member 50, i

an apertured wall member 52,k and cylindrical sections 54, 56 are secured inl clamped relation with the orifice plate 14 by tie-bolts 58. The end portion of cylindrical section S6 abuts. a circular. recessed surface 60 which extendsabout the orifice 34. Resilientv seal-rings62 in appropriate groovesin the. apertured wall member and cylindricalisectiorr 56. A .crcular sealbase 76.issecured,

partially in section,

of Figure 1 on anenlarged scale;

of the actuator of'Figure Zonan enlarged.

and 32 by the orifice.

g l Y piston l36 is positioned in chamber 32`r and is adaptedto seat against the orlice-plate,aas shown` As. shown inFigure l, the thrust column and 66 by" by a bolt 73 to the piston and is provided with a groove in which a circular resilient pressure sealing element 80' is secured as by bonding. Pressure sealing between the valve piston and the seal base is provided by an appropriate seal ring. As shown, circular seal 80 encircles orifice 34 and effects a pressure seal between the piston and the orice plate when the valve piston is seated against the orifice. plate.. As indicated in Figure 3, an annular area 82 of the piston or seal base is disposed outside this circular pressuresealing which is thus eff fected. A deceleration metering pin 84 extends from the side of the piston opposite from the seal base, andv is secured by engagement of its threaded shank portion.86 in an axial .opening in the piston. The metering member has an elongated Section 88 and an enlarged section 90 adapt-ed to cooperate with aperture 68.

A port 92 in the release system casing, a passage 94 in the orifice plate and uidcouplings 96, 98 interconnect a source of set pressure (notshown) with chamber 66in the release system assembly. Chamber 30V ofthe actuator communicates with a source ofactuating pressure (not shown) through a port 100 and. a uid' coupling 102. Tube 106 and radial passage 104 in the orifice plate interconnect orifice-34 and another source of pressure (not shown). Ay fluid coupling 108 (Figure l) provides means for vintroducing pressure from another source (not shown) into chamber `32 ofV the actuator. A similar coupling lltland aport V112 communicate with chamber 32 for a purpose'which is hereinafter explained.

In operation, theactuator ofthe present.invention is capable of imparting very. high level thrust or acceleration to the output thrust. column 40.y A set pressure is rst introduced into chambers 66 and: 64'through openingV 92fluid coupling 96 kand* passage 94. The set pressure acts upon the cross-sectional area of. release piston 72 and'urges the piston against orice plate 14. This compresses circular resilient seal against the recessedA surfacet) of the orificeA plate to effect a positive pressure seal-about .the orifice 34. A high actuatingpressure is established in chamberv 30 to -cause movement of theipistonfrom theorice plate,

and eliminate the pressurerseal provided by. sealing element 80. This may be accomplished in.either of two ways. By one method, the actuating pressure-inchamber 30- is` increasedv by a ditferential sulcient.` to unbalance the forces and cause movement of the piston from the orifice plate.- By-the other method, a triggering pressure is introduced througlrcoupling106and.passage 104 upon the -release piston area withinA circular sealing element 80. This pressure, cooperating with the actuating pressure acting on the piston area outside the sealing element 80`unba1ances=therforces on the` piston and disengagesthev sealing element 280.

Upon elimination ofthe pressureseahthe high actuating pressure is released substantiallyy instantaneously upon the piston area withinsealingfelement.80.. Therelease piston is kthereby impelledwith extremely4 high acceleration fromv the orifice plate or Wall 14as indicated in Figure 4. This releases'the high' actuatingv pressure substantially instantaneously'through the'oriiice to act upon the actuator piston 36. The actuating pressure is thus suddenly applied to the entire areaof the actuator. piston confronting the orice plate, as definedl by peripheral sealing element` 38, on ywhich no substantial pressure had been acting, A great'force is thus applied to the actuator piston to'impel vit fromthe. oritice wall toy producehigh level, actuatortoutput;

Theacceleration .of the release. piston. frounthe orifice through port- 100. and cou-` pling 102. This pressure isexerted through` ports 7Gv The piston is. thus` wall, and therapidity'o'f the release of actuating pres-` sure through the orifice, are functions of the proportion of the release piston area within sealing element 80 relative to the area outside the seal. The greater the area within, the greater is the accelerating force when the sealing element 80 is disengaged.

From the geometric relations of the parts, it will be appreciated that an increase of the lpiston area within the seal may be etfectedconcurrently with increase' in orifice size. Therefore, an important advantage of the present invention is that increased speed in releasing actuating pressure upon the actuator piston is accompanied by decreased orifice losses and by consequent increased force on the actuator piston, thus compounding the advantages provided by the present invention.

From the foregoing description, it will be understood that the actuator of the present invention provides improved output through the utilization of a novel pressure release system for rapidly releasing actuating pressure upon an actuator piston. It will be observed that movement of the actuator piston need not be opposed by any substantial pressure in chamber 32 or by other forces within the actuator. It will therefore be understood that actuator output is not restricted `by internal actuator pressures or forces. As hereinbefore mentioned, the actuator output is enhanced by the rapid application of the actuating pressure to the entire cross-sectional area of the actuator piston. The actuators of the copending applications release actuating pressure upon an increased actuator piston areaafter the actuating pressure has already been applied to a portion of the piston area.

After the release piston have been accelerated from the orice Wall, deceleration metering pin 84 coacts with the aperture 68 of wall member 52 to effect predetermined deceleration of the release piston in the manner described in the copending applications. Thel release piston forces the gas in chamber 66 through the deceleration aperture. The net aperture ow area is varied according to piston position by the longitudinal contour of the deceleration pin to produce predetermined variation in back pressure, in a manner known in the art. It will be understood'that by using an appropriately contoured pin, a desired deceleration-time pattern may be obtained.

l In order to prepare theactuator for repeat operation, the pistons must be reseated against the orifice plate. The actuator piston is reseated against the orifice plate by a relatively low pressure introduced into chamber 32. The release piston must lbe reseated against the orifice plate to re-establish pressure sealing by means of resilient seal 80. In the embodiment describedl hereinbefore, reseating is preferably effected by reducing the pressure in chamber 30and within the orifice to a value below the set pressure in chambers 64 and 6 6, so that the set pressure urges the release piston yagainst theorifice plate. 'i i Upon reseating of the pistons, the trapping of pressure in the space defined between circular sealing element 80 on the release piston and seal 38 on the actuator piston is prevented by relieving pressure through passage' 104 vin the orifice plate., If not released, trapped pressure would act upon the actuator piston area within seal 80 and would oppose the force exerted oppositely on the release piston by the setting pressure. Upon increasing the pressure in chamber 30, the release piston would' be moved and seal 80 would be disengaged by the action ofa relatively low pressure in chamber 30 upon the piston area outside circular seal 80, instead of by the desired actuating pressure. v

` A `modified form of the actuator of the present invention is shown in Figure 5. This embodiment diiers from the embodiment hereinbefore described in that a reseating assembly 114 is provided in the release system assemblyfor moving the release piston against the orice plate preparatory to repeat operation; It alsov differsy in that of the actuator output. A movable apertured'wall member 118 is utilized instead of the xed Wall member'52 of Figure 1. Acylindrical spacer 120 is secured as byv welding between the wall member and a circular `plate 122 to form the reseating assembly 114, which normally' abuts cap member 128. A seal ring 124 in an appropriate peripheral groove in plate 122 provides pressure sealing between the reseating assembly and cylindrical release system casing 126. -It will be observed that cylindrical casing 126, cap member 128 and plate 122 cooperate to define an expansible pressure chamber 130 when plate 122 is spaced from the. cap member. An axial opening 132 in the cap member, a passage 134 angularly spaced from passage 94 (Figure 6), and fluid couplings 136, 138 interconnect chamber 130 4with a source of reseating pressure (not shown)."-This pressure source is also connected with chamber 32 of the actuator by iiuid coupling 108 (Figure 1).

.The contoured metering member 116 is secured to the actuator piston by means of its reduced'threaded end portion 140. The member 116 has a contoured portion 142 and an enlarged portion 144 closely fitting the orifice 34.

To accommodate the metering member, an axial opening 146 is provided in the release piston; Av retainer 148 is' threaded intol this opening and secures an annular seal base 150 to the piston, as shown.

The operation of the embodiment shown in Figures `5 and 6 is like that of the embodiment hereinbefore dis-fl cussed, except for the functions of the metering member 116 and of the reseating assembly 114. The metering member 116 is contoured to control the output thrustf time .or acceleration-time pattern on the thrust column 40, in the manner described in the copending applications hereinbefore identified. After circular sealing element 80 has been disengaged from the orifice Wall and the actuator piston is in motion, the actuating pressure is released upon the actuator piston through a net orifice area gov" erned by the metering member. A pressure drop is produced across the orifice which varies in accordance with this net effective orice area. The net pressure on the actuator piston vand the acceleration force thereon therefore vary in accordance with the net ow area. It

will be understood that a selected acceleration-time. or

thrust-time pattern may be produced by an appropriately:

contoured metering pin. The manner of determining the' contouring of metering members to produce'selected out#V put patterns is set forth in'the copending applications hereinbefore identified.

The reseating of the actuator andrelease pistons is effected in a. different manner than in the case of the embodiment of Figures 1, 2 and 4. A reseating pressure higher than the actuating pressure is utilized. The ac through passage 134 inthe orifice plate, coupling -136- and opening 132 in cap member 128. This pressure moves the reseating -assembly 114 from the cap member 128. As shown in Figure 5, the reseating assemblyis; moved by the actuating pressure into contact with the` release piston 72, and urges the release piston into seating relationship with the orifice plate 14' to re-cstablish the pressure seal about theorice. After the pistons are reseated against the orifice plate, the pressure within the orifice 34 is relieved through passage 104 and coupling` 106. The reseating pressure in chambers 30 and 32.is next relieved, leaving a relatively low pressure in cham-4 ber 32, and permitting the constant set pressure `in' the release systemassembly to reseat the reseatingassemblyv 114 against cap member 128.

It will be understood that utilization of the "s1`u'=.cia1'v reseating assemblyobviates the necessity `for.exhaustingE asaasoe.-

tor.. Economyfof. gas or'uidandisavings of time-are effected. Therreseating pressure' is preferablyappliedhydraulically,; because-af the greater convenience of' generation and-more rapid application ofpressure. When hydraulic,pressureis*v utilized, they fluid is removed from chamber 32;v through, openingl 110i and. coupling 112 in the-:actuator Vliousingfliigure 1) after the'I actuator piston iszseated.

Although specific: embodiments of thepresent invention have been described and illustrated in detail, it is to` beiclearly understood that-the same are by way of illustration and example only; it isy to beunderstood that the inventionfisfnot limited'thereto, as many variations will be-rea`dily=l apparent'to thoseversed in the art and the inventionris` to be: given its broadest possible interpretation within theterms of the appended claims.

The inventor claims:

l. Ani actuator comprising housingI means, a wall defining an orifice-within the housing means, a release pistonpositioned inthe housing means, said release pistonv and said wallbeingadapted for cooperation to pro-- vide a pressure seal therebetween about said orifice,

means for exerting a set force urging the release piston toward-t` the'wall to effect said pressure seal, and means for applying` pressure totherelease piston tooverbalance the; set: force. to eliminate `said f pressurey seal andv expose.

an increased area of the. release pistonk to said pressure; wherebyr therelease piston is` rapidly moved from said wall tozreleasewthe pressure4 throughthe orifice.

2;L An: actuator comprisinghousing means, a wall definingA an orifice within the housing means, an actuator pistonpositioned on a first side of the wall, a release pistonfpositioned on a-secondside of the wall, the release piston and` the wall being adapted for cooperation to providev a pressure sealftherebetween about' said orifice, meansfor exertingl a set force. urging the release piston toward the wall toeffect said pressure seal, and means for. applying pressure to the release piston to overbalance the setti force to eliminate said pressure seal` and expose an increased area of the release piston to said pressure, whereby'the release piston is rapidly moved from said wall to'release the pressure through the orifice upon said actuator piston` 3. An'actuator comprisinghousing means, a wall defining anorifice within the housing means, an actuator piston'positioned" on a 'first` side ofthe wall, a release system-assemblyrpositionedvonv a second side of the wall, a releasepiston slidable inthe release system `assembly and adapted for cooperation with said' wall to'provide a pressure seal4 therebetween about said orifice, means for establishingy a set pressure in said release assembly for exerting a set force to urge the release piston toward the wall to' eflectgsaid pressure seal, and means for establishing an'actuating pressure to act upon the release piston to overbalance the set force to eliminate said pressure seal and Aexpose-anincreased area of the release piston to the actuating pressure, whereby the release piston is rapidly moved-from the wall to release the `actuating'pressure uponxsaid actuator piston;

' 4L An .actuator comprising'housing means, a wall defining anforifice within the housing means, an actuator piston positioned on a first side of said wall, a release piston positioned on a second side lof'the wall and adapted for cooperation therewith to provide a 'pressure seal therebetween about said orice, means for exerting a set force urging the release piston toward the wall to effect said pressure seal, means for' applying an actuating pressure to the release piston to oppose saidset force, 'and means for applying a triggering force to the release piston to cooperate with said actuating pressure in overbalancing the set force to eliminate the pressure seal and expose an increased area of the-releasepiston tothe actuating pressure, whereby the srelease` piston f is` rapidly: moved .from the wall.. toy re- 8i; lease the actuatingv pressure through the lorifice upon said actuator piston.

5. An actuator comprising housing means, a wall delin- -ing an orifice within the housing means, a release system t assembly disposed on 'a first side of the wall, la releasev piston positioned in the release system` assembly, a resilient sealing element positioned between the release piston and the wall for effecting a pressure seal therebetween about said orifice, means forl exerting a set force urging said release piston toward the wall to effect said pressure seal, and means for establishing an actuating pressure to act upon a portion ofthe release piston outside said pressure seal to overbal-auce said set force to eliminate pressure seal and release the actuating pressure upon an increased area of the release piston, whereby the release piston is accelerated from the wall to release the actuatingr pressure through the orifice.

6. An actuator comprising housing means, a wall defining an orifice between first and second chambers within the housing means, an actuator piston positioned in said first chamber, a release system assembly disposed in said second chamber, a release piston positioned in the release system assembly and adapted for cooperation with said wall to provide a pressure seal therebetween about said orifice, means for exerting a set force urging said release piston toward the wall to effect said pressure seal, and means for establishing an actuating pressure in said second chamber-to act upon la portion of the release piston outside said pressure seal to overbalance said set forcev to eliminate said pressure. seal and release the actuating pressure upon an increased area of the release piston, whereby the releasepiston is accelerated from the wall to release the actuating pressure through the orifice upon said actuator piston. l

7. An actuator comprising housing means, a wall defining an orifice between first and second chambers within the housing means, an actuator piston positioned insaid first chamber, a release system assembly disposed in said second chamber, a release piston positioned in the release system assembly andadapted for cooperation with said wall to provide a-pressure seal therebetween about said orifice, means for exerting a set force urging said release piston toward thewall to effect said pressure seal, means for establishing an actuating pressure in said second chamber to act upon a portion of the release piston youtside said pressure seal to oppose said set force, and means for applying a triggering force to the release piston for cooperating with said actuating pressure in overbalancing the set force to expose an increased area of the release piston to the actuating pressure, whereby the release piston is accelerated from the wall to release the actuating pressure through the orifice upon said actuator piston.

8. An actuator comprising housing means, a wall defining an orifice between iirst and second pressure chambers within the housing means, an actuator piston positioned in said first pressure chamber, a release system assembly f disposed in said second pressure chamber, a release piston positioned in the release system assembly, sealing means positioned between the release piston and the wall forl effecting a pressurev seal therebetween about said orifice, means for exerting -a set force urging said release piston toward the wall to effect said pressure seal, and means for establishing an actuating pressure in said second chamber to act upon a portion of the release piston outside said pressure seal to overbalance said set force to eliminate the pressure seal and release the actuating pressure upon `an increased area of the release piston, whereby the release piston is accelerated from the wall to release the actuating pressure through the orifice upon said actuator piston. y

9. An actuator comprising housing means, a wall delining an orifice between first and second pressure chambers within the housing; means, an. actuator piston positioned in-said first-pressure chambena release `system assembly.

disposed in said second vpressure chamber, a release piston positioned in the release system assembly, a resilient seal element for providing a pressure seal between the release piston and the wall about said orifice, means for exerting a set force urging said release piston toward the wall to effect said pressure seal, `means for establishing an actuating pressure in said second chamber tol act upon a portion of the release piston outside said pressure seal to oppose said set force, and means for -applying a triggering force to the release piston for cooperating with said actuating pressu-re in overbalancing the set force to expose an increased area of the release piston to the actuating pressure, whereby the release piston is accelerated from the wall to release the actuating pressure through the orifice upon said actuator piston.

10. An actuator comprising housing means, a wall defining an orifice within the housing means, an actuator piston positioned ron a first side of the wall, a release assembly disposed on a second side of the wall, a release piston positioned in the release assembly and adapted for cooperation with said wall to provide a pressure seal therebetween about said orifice, means for exerting a set force urging the release piston toward the wall to eiiect s-aid pressure seal, and means for applying pressure to the release piston to overbalance the set force to eliminate ,the pressure seal and expose an increased area of the release piston to the pressure, thereby rapidly moving the release piston from the wall to release the pressure through the orice to accelerate said actuator piston, means dening an aperture within the release assembly, means carried by the release piston for regulating iiow through said aperture to decelerate the release piston,

and an output thrust column attached to the actuator pis? ton and extending outside said housing means.

l1. An actuator comprising housing means, a wall dening an orifice within the housing means, an actuator piston positioned on a first side of the wall, a release system assembly positioned on a second side of the-wall, a release piston slidable in therelease assembly and adapted for cooperation with said wall to provide a pressure'seal therebetween about said orifice, means for establishing a set pressure in said releasing system assembly for exerting a set force to urge the release piston toward the wall to eiect said pressure seal, means for establishing pressure to act upon the release piston to overbalance the set force to eliminate said pressure seal and expose an increased area of the release piston to the actuating pressure, therebyrapidly moving the release piston from said wall to release the actuating pressure through the orifice to accelerate said actuator piston, and reseating means actuable within said release system assembly for urging the release piston against the wall to reestablish said pressure seal.

12. An actuator comprising housing means, a wall defining an orifice within the housing means, an actuator piston positioned on a tirst side of the wall, a release system assembly positioned on a second side of the wall, a release piston slidable in the release assembly, a resilient sealing element for effecting a pressure seal between the-release piston and the wall about said orifice, means for establishing a set pressure in said release assembly for exerting a set force to urge the release piston toward the wall to eiect said pressure seal, means for establishing an actuating pressure to act upon the release piston to overbalance the set force to eliminate said pressure seal and expose an increased area of the release piston to the actuating pressure, thereby rapidly moving the release piston from said wall to release the actuating pressure through the orifice upon said actuator piston, and reseating means actuable Within said release assembly for urging the release piston against the wall to reestablish said pressure seal.

13. An actuator comprising a cylindrical housing, a wall dening an orifice between rst and second pressure chambers within the housing, an actuator piston positioned in said rst chamber, a release system assembly attached to said wall and disposed in said second pressure chamber, a release piston positioned within said release system assembly and confronting the wall, said release piston and the wall being adapted for cooperation to provide a pressure seal therebetween about said orifice, means for establishing a set pressure in the release system assembly for exerting a set force urging the release piston against the wall to establish said pressure seal, means for establishing an actuating pressure in said second chamber to act upon a portion of the release piston outside said pressure seal to overbalance the set force and expose an increased area of the release piston to the actuating pressure, thereby accelerating the release piston from the wall to release the actuating pressure through the orifice upon said actuator piston, and a contoured metering member carried by the actuator piston for regulating iiow throughV the orifice to produce a predetermined thrust-time output pattern on the actuator piston.

14. An actuator comprising a cylindrical housing, a wall deiirn'ng an orifice within the housing, a release system assembly attached to said wall and disposed on a first side thereof, a release piston positioned within said release system assembly, a resilient sealing element positioned between the release piston and the wall for eiecting a pressure seal therebetween about said orifice, means for establishing a set pressure in the release system assembly for exerting a set force urging the release piston against the wall to establish said pressure seal, means for establishing an actuating pressure in said rst chamber to act upon a portion of the release piston outside said pressure seal to overbalance the set force and expose an increased area of the release piston to the actuating pressure, thereby accelerating the release piston from said wall to release the actuating pressure through the orifice. t

15. An actuator comprising a cylindrical housing, a wall defining an oriiice between first and second pressure chambers within the housing, an actuator piston positioned in said iirst chamber, a release system assembly attached to said wall and disposed in said second pressure chamber, a release piston positioned within said release system assembly and confronting the wall, a resilient sealing element positioned between the release piston and the wall for eiiecting a pressure seal therebetween about said orifice, means for establishing a set pressure in the release system assembly for exerting a set force urging the release piston against the wall to establish said pressure seal, and means for establishing an actuating pressure in said second chamber to act upon a portion of the release piston outside said pressure seal to overbalance the set force and expose an increased area of the release piston to the actuating pressure, thereby accelerating the release piston from said wall to release the actuating pressure through the orice to accelerate the actuator piston.

16. An actuator comprising housing means, 'a w-all deiining an orifice within the housing means, an actuator piston positioned on a first side of the wall, a release system assembly disposed on a second side of the wall, a release piston slidable in the release system assembly and adapted for cooperation with the wall to provide a pressure seal therebetween about said orifice, means for establishing a set pressure in said release system assembly for exerting a set force to urge the release piston toward the wall to effect said pressure seal, means for establishing an actuating pressure to aet upon a portion of the release pistonoutside the pressure seal to overbalance the set force to eliminate said pressure seal and expose an increased area of the release piston to the actuating pressure, thereby rapidly moving the release piston from the wall to release the actuating pressure through said orifice upon said actuator piston, a contoured metering member on said actuator piston for movement within the orifice for regulating release of the actuating pressure upon the actuator piston .11' to produce a predetermined thrust-timepattern thereon, means defininga restricted aperture within said release system assembly, and a contoured, deceleration pin `on said release piston Vfor movement relative to said apertured wall member to regulate ilow therethrough to `develop predetermined deceleration ot the piston.

l7. An actuator comprising housing means, a wall dening an orice within the housing means, an actuator piston positioned on la Erst side of the wall, a release system assembly disposed on a second side `of the wall, a release piston slidab-le in the release assembly and adapted for cooperation with said wall to provide a pressure seal therebetween about said orifice, means vfor establishing a set pressure in said release 'assembly for exerting a set force to urge the releasepiston toward the wall to effect said pressure seal, means for establishing an acutating pressure `to lact upon a. release piston area outside the pressure seal to overbalance the set force to eliminate said pressure seal and expose an increased area of the release piston to the actuating pressure, thereby rapidly moving the release piston from the wall to release the actuating pressure through the orice upon said actuator piston, an apertured wall member slidably positioned in said release system assembly, a contoured deceleration pin on said release piston for movement relative to said aperturedv wall member to regulate flow therethrough to develop predetermined deceleration of the releasepiston, means cooperating with said apertured wall member to providev a movable reseating assembly in the release system assembly, and means for establishing a reseating pressure 4in the release system assembly to move the reseating assembly against the actu-ating pressure to reseat the release piston against said wall.

18. An actuator comprising a cylindrical housing, a

Wall defining an orifice between first and second pressure chambers within the housing, an actuator piston positioned in said rst chamber and confronting said wall, a release system assembly attached to said Wall andedisposed in said second chamber, a release piston positioned in said release system assembly, a resilient sealing element for providing a pressure seal between therelease piston and actuator piston, means for `decelerating the release piston,

and an `output thrust column attached to the actuator piston.

19. An actuator comprising @a cylindrical housing, a wall having an orifice and separating rst and second pressure chambers within the housing, an actuator piston positionedin said lirst chamber and confronting said wall,l

a release system assembly attached to the wall and disposed in said second chamber, a release piston positioned in said release system assembly, a resilient sealing element positioned between the release piston and the wall for etecting a pressure seal therebetween Iabout said oriice, means for establishing a set pressure in the release system assembly for exerting a set force urging the release piston against the wallto establish said pressure seal, means for establishing an actuating pressure in said second chamber to act upon a portion of the release piston outside said pressure seal .to overbalance the set force and expose 1an increased area of the release piston to the actuating pressure, and means actuable within the release system assembly for urging the release piston toward said orifice wall against the actuating pressure to re-establish said pressure seal.

References Cited in the tile of this patent UNITED STATES PATENTS 

